Often it is required to find figure perimeter in tasks in geometry. Perimeter of a figure is called length of the line limiting it. It is possible just to measure length of this line, of course. However, results of such measurements can be insufficiently exact. Besides, measurement of length of a curve – pretty difficult process. Therefore in practice and at the solution of geometrical tasks usually use special formulas.
It is required to you
- ruler, compasses, calculator
Instruction
1. To find figure perimeter, the limited broken line, put lengths of all pieces making it. If lengths of pieces are unknown, measure them by means of compasses and a ruler. If the figure has rather big sizes, use a roulette. As unit of measure of perimeter will serve the same units in which are set lengths of the making pieces (were measured). If units of measure different, then them it is necessary to lead to one look. For example, if the land plot has triangular shape with lengths of parties of 10, 20 and 30 meters, respectively, its perimeter will make that: 10 + 20 + 30 (m).
2. For finding of perimeter of simple geometrical figures, use special formulas. To find rhombus perimeter (in particular, a square), increase length of its party by four. That is, use the following formulas: P (rhombus) = P (square) = 4 * with, where with – length of the party of a rhombus (square), P – its perimeter.
3. For finding of perimeter of a parallelogram (in particular, a rectangle), put its length and width and increase by two (length and width are meant as lengths of two adjacent parties). More visually, it can be written down in the following look: P (parallelogram) = P (rectangle) = 2 * (d + x), where: d both highway – length and width of a parallelogram (rectangle), respectively.
4. To find circle perimeter, calculate length of the circle limiting it. For this purpose use a classical formula: P (circle) = π * D ilip (circle) = 2 * π * P, where: Д – diameter of a circle, P – circle radius, π – number "пи", approximately equal 3.14.
5. If square diagonal length is known, then for finding of its perimeter use the following formula: P (square) = 2√2 * d, where d – square diagonal length.
6. The perimeter of a square can be calculated, using information on its area. For this purpose use the following rule: P (square) = 4 * skv where Skv is the area of a square.